Method of forming gravel packs for wells



Feb. 25, 1930. T. w@ THORPE A 1,748,589

METHOD 0F FORMING GRAVEL PACKS FOR WELLS Filed March 28, 1928 l 2Sheets-Sheet l Feb. 25, 1930. T. w. THoRPE 1,748,589

METHOD OF FORMING GRAVEL PACKS FOR WELLS Filed Maren 28, 1928zsneets-snwh 2 FI? E 41 /WMZ; W

:HIIIIIM 4 @22M/falaz* Patented Feb. z5, 1930 UNITED vssivmsleivrltla'rA `OFI-ICE THOMAS W. THORPE, OF DES MOINES, IOWA, ASSIGNOR TOTHORPE BROTHERS WELL GOMPIANY, OF DES MOINES, IOWA, A COPARTNERSHIPCOMPOSED 0F GEORGE E. THORPE, WALTER T. THORPE, AND THOMAS W. THORPE.

METHOD OF FORMIN'G GRAVEL PACKS FOR WELLS Application vled March28,1928. Serial No. 265,250.

The object of my invention is to provide a method whereby gravelpacksmay be conveniently and easily formed for wells, the method itselfbeing comparatively inexpensive to perform.

A further object is to form a gravel pack in a stratum of water bearingsaid whereby water may be pumped from a well in considerable quantitieswithout running short of water which would be the case where no gravelpack is formed due to the fact that the stratum of water bearing sandincludes a fine sand through which it is very dilcult for the waterftoass quickly.

Still a ther object is to provide a method wherein a main casing isinserted in the ground down to the stratum of water bearing sand and oneor more auxiliary casings are with gravel and to provide in the -methodinserted in the ground spaced from the main casing. The auxiliarycasings serving to receive gravel whereby pumping of the sand from themain casing will cause the gravel in the auxiliary casing or casings tosettle downwardly and take the place of the sand that has been pumpedout of the stratum.

Still a further object is to perform Uthe method for displacing the sandpumped out means for manipulating the auxiliary casings for insuringthat a large gravel pack will be formed.

With these and other objects in view my invention consists in thelereindescribed method of forming gravel packs for wells whereby the objectscontemplated are attained, as

hereinafter more fully set forth, pointed out in my claims andillustrated in the accon'ipanymg drawings, in which:

Figure 1 is a plan view illustrating a main casing and a plurality ofauxiliary casings inserted i' n the ground. Figure 2 is a crosssectional view on the line 2--2 of Figure 1 illustrating-the casings andtheir relation to the various strata formed in the round.

Flgure 3 is a similar sectional view illustrating the method inoperation and showing a bucket pump for removing the water bearin sandfrom the main casing.

igure 4 is a similar sectional view illustively large gravel pack hasbeen formed around the main casing.

Figure 5 is a similar sectional view illu'strating the auxiliarycasingsinserted downwardly into the stratum of the water bearing sand tofurther displace the water bearing sandwith gravel. Figure 6 isa similarsectional view illus,- trating the insertion of means in one of theauxiliary casings for introducing additional gravel or water forproperly forming the gravel pack. Y

Figure 7 is a sectional View on the line 7 -7' of Figure 5 illustratingthe relation of the gravel pack to the main and auxiliary casings; and

Figure 8 is a similar sectional view 'showing the gravel pack morecompletely formed. On the accompanying drawings I have used thereference numeral 10 to indicate a main casing. The main casing 10 isthe one used for pumping water from the well after it is completed andmay be insertedinto the ground 12 as illustrated in Figure 2 by anysuitable'well boring apparatus. The casing 10 is extended ydownwardlythrough :the ground 12 to a stratum of water bearing sand` 14 asillustrated in Figure 2 after which `a strainer 16 is extended beyondthe lower end of the casing 10 and has its lower end terminatingadjacent a stratum 18 of rock or the like which usually occurs below thestratum of water bearing sand. The strainer 16 is generally supported ona shoe 15 to which is connected a sleeve 17 extending up to the wellboring machine whereby the strainer and shoe may be raised or lowered asdesired. As illustrated in Figure 3 instead of using the strainer 16 thecasinglO itself may be extended to terminate adjacent the stratum ofrock 18.

In the usual formation ofwells as much as possible of the water bearingsaid-14 is re-V moved by pumping it from the casing 10. The pumping maybe done either by any suitable type of pump lowered into the casing 10for pumping the water and sand up 'to the surface of the ound or abucket pump 20 as illustrated in igure 3 may be used which is operatedby moving the bucket up and down, the bucket itself having a valve inthe lower end so that the sand and water may flow into the bucket andthen be lifted upwardly. In the use of my method either type of removingthe sand and water may be utilized. Ihe usual practice is to pour gravelinto the casing 10 after as much as possible of the water bearing sandhas been removed and letting this gravel form a pack for the purpose ofproviding a quantity of gravel through which the water may flow rapidlyso that the capacity of the well is considerably increased by such apack.

It is obvious that the larger the pack the greater will be the capacityof the well. It is therefore my purpose to provide a method whereby acomparatively large gravel pack may be formed.

To accomplish this result I insert auxiliary casings 22 in the ground 12which may be done by boring smaller openings surrounding and spaced fromthe main casing 10. One or more of the casings 22 may be used dependingon the condition of the stratum of water bearing sand 14 which in somecases may be a soft sandstone which would require more casings 22 thanwhere the nature of the sand i 14 is similar to quick sand.

The casings 22 may be inserted into the upper part of the stratum 14 asillustrated in Figure 2 or may be inserted further into the sand 14 fora purpose which will hereinafter be referred to.

Practical operation In the operation of my method the water bearing sand14 is pumped upwardly through the casing 10 as indicated by the arrows24 in Figure 2. This forms a cavity in the sand itself and to form thegravel pack this cavity must be lled with gravel. To accomplish this Ipile adjacent each auxiliary casing 22 a pile of gravel 26. The gravel26 is poured or scooped into the rcasings 22 until they are full.

V Then when the pumping is started and the sand 14 is pumped up thelcasing 10 the weight of the gra-vel 26 will cause it to move downwardlyin the casings 22 and displace or take the place of the sand vwhich hasbeen removed as illustrated in Figure 3 of the drawings.

h During the operation of the method the gravel 26 is continuallysupplied to the casin s 22 for keeping them filled.

t will be noted in Figure 3 that the formation of the gravel pack is ina path from the lower ends of the casings 22, to the lower end of thecasing 10. When the pack has been formed as illustrated in Figure 3 andthe pumping is continued, gravel will start coming up the casing 10which will indicate that the pack has been formed. It is desirable,however, to have the pack formed as illustrated in Figure 4 which willresult in case of the stratum 14 being of fine sand. Where the stratum14 is somewhat harder, however, as when being of sand stone, theformation in Figure 3 will occur.

If it is desirable to form the pack larger than illustrated in Figure 3,the casings 22 may be inserted into the stratum of sand 14 asillustrated in Figure 5 which will result in the pack being formed asshown. To form a proper pack the piles of gravel 26 are equal in volumeso that the auxiliary casings 22 mayl be supplied with equal vquantitiesof gravel. In case that one of the casings 22 does not take the gravelas fast as the other ones so that the sand assumes a formation asillustrated by the dotted lines 28 in Figure 6, a pipe 30 may beinserted in this casing 22 and water or gravel and water may be forceddown through the pipe 30 for loosening the sand as indicated by thearrows 32.

The gravel pack when being formed in fine sand will assume the outlineillustrated in Figure 8. Where the stratum 14 is of sand stone or thelike the formation may be as illustrated in Figure 7. In the latter caseif a bigger pack is desired it is necessary to insert auxiliary casings22a into the ground so that the spoke like formation will have a greaternumber of spokes and consequently a greater volume of gravel in thepack.

From the foregoing description it will be apparent that I have provideda method for forming gravel packs wherein the natural tendency of thegravel is to displace the water bearing sand being withdrawn from themain casing. The method is much more eiiicient than trying to blast alarge opening adjacent the lower end of the casing where the force ofthe explosion tries to drive a portion of the water bearing sand againstthe great body of sand composed of the rest of the stratum.

The capacity of a well having a gravel pack of this character is greatlyincreased over the capacity of ordinary wells wherein a smaller gravelpack is formed by other methods. The size of the gravel pack may beincreased or decreased as desired by regulating the distance of theauxiliary casings 22 with respect to the main casing v10.

If the stratum 14 is of such hard material that it is difficult toremove it and displace it with gravel, the stratum may he loosened byblasting before the pumping is started.

Some deviation from the method herein disclosed and described may occurwithout departing from the real spirit andl purpose of my invention, andit is my intention to cover by my claims, any modified methods or use ofmechanical equivalents, which may be reasonably. included within theirscope.

I claim as my invention:

1. A method of forming a gravel pack for a well comprising the boring ofa main opening downwardly to water bearing sand, the

boring of a plurality of auxiliary openings surrounding and spaced fromsaid main through one of the wells to replace iine mateopening, thepumping of the water bearing rial removed from the stratum w1th watersand from the main opening and the supplypumped through the other well.ing of gravel to the auxiliary openings. Des Momes, Iowa, February 21,1928.

2. A method of forming a gravel pack for THOMAS W. THORPE. a wellcomprising the insertmg through an opening of a casing into the grounddownwardly to water bearing sand, the inserting through a second openingof a second casing downwardly to water bearing sand, the withi i vdrawal of the water bearing sand through said first casin andtheintroducing of gravel into said secon casing whereby a gravel pack maybe formed between the lower ends of the l two casings.

3. A method of forming a gravely pack for a well comprising theinserting of a main casing through an opening in the ground downwardlyto water bearing sand, the inserting of an auxiliary casing through asecond opening downwardly to water bearing sand, the pumping of the sandVfrom the space between the lower ends of the casings and theintroducing of gravel into said auxiliary casing whereby the gravel willdisplace the sand being pumped out and the forming of a gravel packwillresult.

4. A method for forming a gravel pack comprising the inserting of acasing through an opening in the ground and partially through a stratumof water bearing sand to v a position with the lower end of the casingspaced from a stratum below the water bearing sand, the inserting of asecond casing through a second opening spaced from the 100.

first one in the ground partially through the stratum of water bearingsand, the supplying of gravel to the second casing and the pumping ofthe water` bearing sand from below the first casing. 5. A method forforming a gravel pack 1 Y comprising the sinking of two separate wellsto a stratum of water bearing sand, the ren moving of such sand from oneof said wells andthe su plying ofgravel to the other well r 110 wherebyt e gravel displaces the sand being pumped from the lirst well andthereby lls the space in the stratum between said two wells.

6. A method of forming a gravel pack in 115 a stratum of water bearingsand comprising the formin of spaced openings from they surface of t eground to the topof said stratum, one of said openings to serve as are'- ception opening and the other opening to 180 serve as a dischargeopening, the withdrawal of the water bearing sand from the dischargeopening and the introduction of gravel into the reception openingwhereby the avel settles by gravit and fills the space 1n the 125stratum of water aring sand from which the sand has been withdrawn. 7.The method of making and maintaining a well including sinking separatewells' to a water stratum, and supplying gravel`

